Diesel engine fuel



Patented Apr. 15, 1941 DIESEL ENGINE FUEL Marvin L. Chappell, Berkeley,Calif., assignor to Standard Oil Company of California, San Francisco,Calii'., a corporation of Delaware No Drawing.

Application March 14, 1938,

Serial N0. 195,823

5 Claims.

This invention relates to fuel boiling above the gasoline range and toprimers produced therein for the purpose of lowering its spontaneousignition temperature when used in internal combustion engines with fuelinjection at the end of the compression stroke.

Fuel oil containing such accelerators or primers is used chiefly tooperate internal combustion engines of the Diesel or semi-Diesel type inwhich ignition of the fuel is efiected by the heat developed in thecompression of the air.

It has been previously proposed to add to Diesel fuel a small percentageof an ignition accelerator of the explosive type, such as peroxides,nitro-compounds, perborates, persulfates and the like, which lower thespontaneous ignition temperatures of the fuel oil itself. However,agents of the explosive type are dangerous to handle, unstable, and maybe decomposed after addition to the'fuel when stored for a period oftime before use.

Now, I have discovered improvements in the product and process forlowering the ignition temperature of Diesel engine fuels, by producingtherein diazonium salt reaction products with constituents of the fuel,among which products may be included some compounds probably in thenature of azo compounds, which is accomplished by treating the fuel witha diazonium acid salt at temperatures preferably below 40 F., thenneutralizing the treated fuel mixture with a water solution of an alkalihydroxide and finally separating the water containing dissolved salts ofreaction from the treated fuel containing the diazonium salt reactionproducts in solution.

I have discovered that this type of diazonium salt reaction productsproduced in the fuel by the aforesaid method is stable and sufiicientlysensitive to facilitate combustion to the desired deree, the percentagerequired depending upon the character of the hydrocarbon composition ofthe fuel and the type of Diesel engine in which the An object of theinvention is to produce a new motor fuel by an improved process oftreating petroleum oil or petroleum oil products, with an agent capableof converting a part thereof into primers or lower ignition products ofthe type resulting from the diazonium salt reaction with constituents inthe petroleum oil or petroleum oil products.

Another object of the invention is to produce a new fuel for Diesel typeengines with an ignition temperature sufllciently low to suit the enginein which it is to be used.

Various other objects and advantages of the present invention will beapparent from the following example which illustrates in general thepreferred method of preparing the new fuel sensitized to the degreenecessary for the type of engine in which it is to be used.

Dieselfuel prepared from petroleum oil, petroleum residuum, petroleumdistillate or petroleum residuum mixed with distillate, maintained at atemperature below 40 F., preferably at about 32 F., is commingled withan acid water solution of a diazonium acid salt, and thereafterneutralized with a water solution of an alkali with continuous coolingsuflicient to maintain the temperature of the mixture below 40 F. untilthe azo reaction is complete. Thereafter the treated fuel mixture israised to a higher temperature and the water containing thedissolved'salts of the neutralizing reaction is separated from thetreated fuel containing the diazonium salt reaction products insolution.

The diazonium acid salt for the treating operation is made by any of thewell known methods of treating primary aromatic amine salts at lowtemperatures with nitrous acid in the presence of a suflicient quantityof acid to form the salt desired. Preferably, a water solution ofsodium, potassium or amyl nitrite followed by an addition of acid todecompose the salt, is used to form the nitrous acid required for thedi-azo reaction, although any other nitrous acid salts may be used inconjunction with the required quantity of acid to transform the nitriteused into the acid. The acid used to decompose the nitrite salt and alsoto form the diazonium salt may be hydrochloric, sulfuric, hydrobromic,acetic and the like.

The preferred method of producing a water solution of a diazonium saltand treating the Diesel fuel by this invention is as follows:

93 parts by weight aniline, 121 parts by weight 7 xylidine, or 143 partsby weight naphthylamine is dissolved in 2300 parts by weight of a watersolution of hydrochloric acid containing 88 parts by weight HCl, andthen cooled to 32 F. To the above mixture 73 parts by weight nitrite ofsoda dissolved in 300 parts of water is added slowly with thoroughmixing and continuous cooling so that the temperature will not exceed 35F, until the diazotizing reaction is complete. This water soolution ofbenzenediazonium chloride is then commingled with 4650 parts by weightDiesel fuel, in case 2% of aniline is required to produce the necessaryquantity of diazonium salt reaction product to raise the cetane numberof the fuel to the required degree. After mixing the benzenediazoniumchloride with the Diesel fuel the diazonium salt reaction is completedby neutralizing the excess acid with a water solution of sodiumhydroxide or other neutralizing agent at a maintained temperature not toexceed 40 F. Thereafter the water containing dissolved salts of thereaction is separated from the treated fuel containing the diazoniumsalt reaction products in solution.

- The following illustrates the eiiectof treating a standard Diesel fuelof gas oil stock derived by distillation of California crude petroleum,with varying percentages of diazonium acid salts in terms of anilineused:

The above example illustrates one method of treating Diesel fuel toraise the cetane number in which the per cent of diazonium acid saltusedmay vary through a wide range and the fuel so treated may be compoundedwith other fuels to increase the cetane number of the mixture.

While the product herein described illustrates a new motor fuel and aprocess of manufacture thereof, various modifications and changes may bemade without departing from the spirit of. the invention, and theinvention includes all such modifications and changes as appear withinthe scope of the appended claims.

I claim:

1. The method of increasing the cetane number of a petroleum Diesel oilfraction boiling in the Diesel oil range and suitable for use as aDiesel fuel but having an undesirably low cetane number, which comprisestreating said Diesel oil fraction with a diazonium salt at temperaturesbelow about 40 F., in proportion suflicient to form diazonium saltreaction products in said Diesel oil fraction and to increase the cetanenumber, neutralizing the resulting mixture, and separating the water.containing the dissolved salts of reaction from the Diesel oil fractioncontaining the diazonium salt reaction products in solution. I

2. The method of increasing the cetane number of a petroleum Diesel oilfraction boiling in the Diesel oil range and suitable for use as aDiesel fuel but having an undesirably low cetane number, which comprisesreacting said'Diesel oil fraction with a diazonium salt at temperaturesbelow about 40 F., in proportion sufllcient to form diazonium saltreaction products with constltuents of said Diesel oil fraction and toincrease the cetane number, neutralizing the resulting mixture, andseparating the water containing the dissolved salts of reaction from theDiesel oil fraction containing the diazonium salt reaction products insolution.

3. In a process of lowering the ignition temperature of a Diesel fuelboiling in the Diesel fuel range, the steps which comprise diazotizing aprimary aromatic amine salt in a water solution containing acid,treating said Diesel fuel with the resulting diazotized solution, andneutralizing the treated fuel at temperatures below 40 F.

4. The method of increasing the cetane number of a petroleum Diesel oilfraction boiling in the Diesel oil range andsuitable for use as a Dieselfuel but having an undesirably low cetane number, which comprisestreating said Diesel oil fraction with benzene diazonium chloride at atemperature below about 40 F. in proportion sufficient to form benzenediazonium chloride reaction products in said Diesel oil fraction andincrease the cetane number, neutralizing the resulting mixture'andseparating the water containing the dissolved salts of reaction from theDiesel oil fraction containing the benzene diazonium chloride reactionproducts in solution.

5. The method of increasing the cetane number of a petroleum Diesel oilfraction boiling in the Diesel oil range and suitable for use as aDiesel fuel but having an undesirably low cetane number, which comprisesreacting said Diesel oil fraction with benzene diazonium chloride at atemperature below about 40 F. in proportion sufflcient to form benzenediazonium chloride reaction products with constituents of said Dieseloil fraction and increase the cetane number, neutralizing the resultingmixture, and separating the water containing the dissolved salts ofreaction from the Diesel oil fraction containing the benzene diazoniumchloride reaction products in solution.

MARVIN L. CHAPPELL.

